Manning had missed four earlier kicks, including a close range conversion which smacked back off a post, but the New Zealander coolly added the extras to Hurley's score and Munster controlled possession off the restart to see out their second successive league win.
The Scarlets, beaten in Glasgow last weekend, had the winning of this game. They grabbed tries, either side of half-time, from prop Deacon Manu and inspirational captain Mark Jones.
Taking over the kicking duties from an out of sorts Rhys Priestland, young full-back Daniel Evans booted a 73rd minute penalty to nudge the Scarlets into a 20-15 lead.
But, with replacement scrum half Tomas O'Leary getting Munster back within scoring range, Hurley was able to scorch past Manu and brush aside debutant Gareth Maule on the way to the try-line.
O'Leary was sprung from the bench for his first appearance since breaking his ankle against the same opposition last April.
The Scarlets were fired up for a big performance, having lost 18-16 to Munster in their first outing at Parc y Scarlets last November.
Nigel Davies made two changes to the side that went down to Glasgow, with Maule making his competitive debut in the centre and player-coach Simon Easterby restored to the back row.
Toby Morland, partnering his old school-mate Manning at half-back, and front rowers Damien Varley and Julien Brugnaut were the only changes to the Munster side that beat Cardiff at home.
The Scarlets made an encouraging start, getting their offloading game going and pinning Munster back in their half.
Munster showed a lack of control at the breakdown and leaked a series of early penalties, two of which had Priestland lining up for goal.
The Scarlets stand-off was off target with both kicks, but the hosts gained a numerical advantage on 10 minutes when Munster number 8 Denis Leamy was sin-binned for coming in at the side of a ruck.
Munster were living on the edge at rucks as the Scarlets piled forward. After a further warning from referee Alain Rolland to Munster captain Mick O'Driscoll, Priestland opened the scoring with a penalty from closer in.
Davies' men were bossing possession at this stage, however Munster drew level from Manning's second penalty attempt and Doug Howlett and Hurley enjoyed excursions into Scarlets territory.
On 24 minutes, the hosts' failure to build on that early pressure was underlined by Hurley's first competitive try for Munster.
The visiting forwards made headway up towards the posts and a floated pass from busy scrum half Morland put Hurley haring in at the left corner, exposing some poor defensive positioning from Sean Lamont.
Manning converted impressively from the touchline but missed a subsequent penalty and Munster suffered another setback on the half-hour when they lost lock Donnacha Ryan to the sin-bin.
Ryan was adjudged to have tackled Daniel Evans in the air, but it was harsh decision on viewing the replay.
The Scarlets did not mind and they scored one of the tries of the season soon after, racing almost the length of the field just when Munster were stepping it up a gear in the forwards.
The champions coughed up possession on the Scarlets 22 and big winger Lamont, running the ball back into the Munster half, took the opportunity to stretch his legs after a quick pass from Easterby.
The former Ireland flanker was involved in the flowing move again, popping up after a surging run from Jonathan Davies to deliver the try-scoring pass to a delighted Manu.
Priestland's conversion brought the sides level at 10-10 for half-time and deservedly so, given the hard work of the likes of Martin Roberts, Maule and David Lyons.
Munster were only allowed to play in fits and starts in the opening half. One of their best moments in attack came when Doug Howlett drove forward in midfield and offloaded out of the tackle to Barry Murphy, the Scarlets looked in trouble but Murphy's attempted pass was knocked on by Lifeimi Mafi.
Munster went behind again, just five minutes into the second half. Maule did well to set up a half-break for Evans and after some more donkey work from the forwards, skipper Jones took Priestland's pass, slipped out of an initial tackle and was driven over from five metres out.
Priestland added the conversion for a 17-10 advantage but the Scarlets were hit with a sucker-punch blow on 53 minutes when Morland scored an opportunistic try - his first in Munster red.
The Scarlets had scrum ball, five metres from their line. However, scrum half Roberts was robbed of the ball as he tried to clear, with Morland and Alan Quinlan right up in his face and the former Chiefs player sneaked over for the try.
Manning's attempted conversion hit the woodwork and the tension increased as both kickers missed penalty efforts.
Evans, taking over the kicking reins, looked to have won it for the Scarlets with a well-struck penalty from a central position.
Displaying the never-say-die attitude they have become famous for, Munster gained ground through their forwards with O'Driscoll, Leamy and replacement Tony Buckley forcing their way through.
Time was against Tony McGahan's charges but a defensive lapse on the left, which saw Hurley dart past Manu and the otherwise impressive Maule, allowed Munster rescue victory from the jaws of defeat.
Credit to Hurley though, he showed a neat turn of pace to make the incision and he also did well to get the ball down under pressure from the retreating Lamont.
As the shellshocked Scarlets stood behind the posts, Manning composed himself sufficiently to kick Munster to their eighth successive win over the men from Llanelli since a European Cup quarter-final defeat at the old Stradey Park in March 2007.
|Scarlets Score Card|
|Munster Rugby Score Card|